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From "Pinaki Poddar" <ppod...@bea.com>
Subject RE: composite ID based on "one" side of a bidirectional one-many relationship
Date Wed, 28 Mar 2007 21:49:20 GMT
Page can have a primary key field type of "Book".

@IdClass(com.mycompany.book.PageId.class)
@Entity
public class Page {
  @Id
  int number;

  @Id
  @ManyToOne
  private Book book;
}

public class PageId {
   int number;
   String book; // the type "String" must match the type of primary key
used in Book.java
                         // the name of the variable "book" must match
the name of the variable in Page class.
}

public class Book {
   @Id
   String title;   
}

 


Pinaki Poddar
BEA Systems
415.402.7317  


-----Original Message-----
From: jeff [mailto:jeffrey.blattman@yahoo.com] 
Sent: Wednesday, March 28, 2007 4:35 PM
To: open-jpa-dev@incubator.apache.org
Subject: RE: composite ID based on "one" side of a bidirectional
one-many relationship

hi,

abe closed this with the reasoning ...

"the book field in the PageId class must be of type String to match the
primary key field type of Book"

was i mistaken when i understood you to say that Page could have a PK
field of type Book? if not, very sorry for all the confusion.

or were you just saying that open JPA allowed the PK field to be a
ManyToOne relationship?

p.s., it's issue #191
https://issues.apache.org/jira/browse/OPENJPA-191

Patrick Linskey <plinskey@bea.com> wrote: Yes, please do. It looks like
your code should work.

-Patrick

--
Patrick Linskey
BEA Systems, Inc. 

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> -----Original Message-----
> From: jeff [mailto:jeffrey.blattman@yahoo.com]
> Sent: Wednesday, March 28, 2007 10:31 AM
> To: open-jpa-dev@incubator.apache.org
> Subject: RE: composite ID based on "one" side of a bidirectional 
> one-many relationship
> 
> yes, i see the problem w/ the attached classes, and with a completely 
> different model where i am trying to accomplish the same thing.
> 
> should i file a bug? i can attach the test case there. 
> 
> Patrick Linskey
 wrote: Are you still 
> seeing that same problem with the code that you attached?
> 
> -Patrick
> 
> --
> Patrick Linskey
> BEA Systems, Inc. 
> 
> ______________________________________________________________
> _________
> Notice:  This email message, together with any attachments, may 
> contain information  of  BEA Systems,  Inc.,  its subsidiaries  and 
> affiliated entities,  that may be confidential,  proprietary, 
> copyrighted  and/or legally privileged, and is intended solely for the

> use of the individual or entity named in this message. If you are not 
> the intended recipient, and have received this message in error, 
> please immediately return this by email and then delete it.
> 
> > -----Original Message-----
> > From: jeff [mailto:jeffrey.blattman@yahoo.com]
> > Sent: Tuesday, March 27, 2007 1:42 PM
> > To: open-jpa-dev@incubator.apache.org
> > Subject: RE: composite ID based on "one" side of a bidirectional 
> > one-many relationship
> > 
> > Patrick Linskey
>  wrote:
> > 
> >  > my ID class has a book field, and getters and setters for it  > 
> > to match Page's book field. i wonder about the last line  > where it

> > says "java.lang.String". that seems odd.
> >  
> >  Can you post your Book and Page classes and the Page's IdClass?
> >  
> > 
> > attached. i keep trying to attach the entire project as a zip, but 
> > apache's spam filter keeps dropping it. let me know i could send to 
> > you directly.
> > 
> > 
> >  > so, regardless, even if that did work, correct me if i am  > 
> > wrong, but it'd be a really bad idea to depend on openjpa  > 
> > specifics, because my app doesn't get to choose the JPA  > 
> > implementation, it has to use whatever the java ee container  > 
> > gives it ... right?
> >  
> >  No -- a Java EE 5 container *must* allow you to specify your 
> > persistence  provider. Whatever you put in the element in the  
> > persistence.xml must be obeyed. Only if you do not specify a  
> > element can the implementation can choose whatever it wants to use.
> >  
> > 
> > yes, duh. sorry.
> > 
> > 
> > 
> >  Correct.
> >  
> >  > so, assuming i do need to accomplish this, is there a best  > 
> > practice? as i mentioned, what i did to make it work was make  > the

> > Page's composite ID incorporate the Book's ID by adding a  > 
> > "derived" bookName field to Page, like ...
> >  
> >  You could add a private bookName field that has no external 
> > mutators or  accessors, and create a @PreStore callback that copies 
> > the value from  the related Book into the field. That would do a 
> > decent job of isolating  the artifact from the rest of your app.
> >  
> > 
> > yes, that works.
> > 
> > ________________________________
> > 
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> 
> Notice:  This email message, together with any attachments, may 
> contain information  of  BEA Systems,  Inc.,  its subsidiaries  and  
> affiliated entities,  that may be confidential,  proprietary,  
> copyrighted  and/or legally privileged, and is intended solely for the

> use of the individual or entity named in this message. If you are not 
> the intended recipient, and have received this message in error, 
> please immediately return this by email and then delete it.
> 
> 
> 
>  
> ---------------------------------
> Food fight? Enjoy some healthy debate
> in the Yahoo! Answers Food & Drink Q&A.
> 

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